BoP Lab / Buttonwillow Raceway Park

F500 vs SRF vs P1 pace at Buttonwillow Raceway Park

Quickest here: F500 1:58.561 Lance Spiering, Super Tour Feb 2022 race · SRF 1:44.060 Vince Balch, Super Tour Apr 2017 qualifying · P1 1:06.404 Chip Romer, Super Tour Feb 2023 qualifying

Lap times% of F500

F500SRFP1solid race · dashed qualifying · slower is lower

F500SRFP1solid race · dashed qualifying · each class's best lap as a share of F500's at the same event (the reference class, changeable above); 100% is level, higher is quicker

	Event	F500			SRF					P1
	Event	Qual best	Race best	Trap	Qual best	Race best	Trap	vs F500	% of F500	Qual best	Race best	Trap	vs F500	% of F500
	Super Tour Feb 2024 CALCL242024-02-23									1:33.133Chip Romer · fastest of 7 · top 5 within 5.2s+26.729s (+40.25%)	1:34.989Chip Romer · fastest of 7 · top 5 within 4.0s+0.779s (+0.83%)	138.2Aaron Bailey-0.2 mph (-0.2%)
15 rule changes (SRF: 7, P1: 8)2 tyres & wheels · 2 weight · 1 aero · 1 engine · 1 suspension & brakes · 5 wording · 3 other · P1 Engine Table line H restrictor grows to 32 mm, weight rises to 1450 lbs; line I restrictor to 31 mm, weight to 1475 lbs. · P1 Group CN Honda K20A-FD2 removes engine modification restrictions; CRB may add intake restrictor if needed. · SRF rain/brake light must be Super Bright LEDs Inc. P/N PT-STRB-R24; secondary filament must connect to rain light switch. · SRF brake light must be Super Bright LEDs Inc. P/N PT-STRB-R24, with SCCA Enterprises P/N 180427A pigtail and strobing rain light kit. · SRF adds mandatory front brake ducts 12–36 inches, throttle pedal heel-toe extension, braided stainless flex lines, camber limit 5.0 degrees, radiator opening height 3½ ± ½ inches, rear shift cable clamp P/N WM302007A. · SRF radiator options expanded: Enterprises P/N 480465 with baffle 480464, 480466, or Automotive 1R698 and CU698 allowed if cross-reference equivalent. · P1 SIR testing: vehicle deemed compliant if it stalls within 3 seconds of the stall test. · P1 intake restrictor rule clarified: flat plate, venturi, or Single Inlet Restrictor required; all intake air must pass through. · P1 ducted air rule clarified: top-exit ducted air must pass through heat exchanger, except cockpit opening and engine bay vents. · SRF wet front tyre changes to Hoosier P/N 46100 P185/60R13 H20 or W2 with 2.5" ground clearance. · SRF front W2 rain tyre Hoosier part number changes from 46100 to 46101 P185/65R13. · P1 aero height limit, front/rear overhang, and cockpit dimensions corrected to metric-inch equivalents. · P1 suspension covers must have symmetrical upper and lower surfaces, no airfoil cross-sections or angled downforce. · SRF removes 1985 Renault Alliance solid front rotor option; restrictor sizes decrease 1mm for newer Kawasaki and multi-brand engines; minimum weights increase to 1100 lbs.showhide 2024-01-01 P1 Please correct omitted punctuation #34890weight 2024-01-01 P1 Adjust restrictors and weights for Engine Table lines H and I #35229weightslower · weightP1 Engine Table line H restrictor grows to 32 mm, weight rises to 1450 lbs; line I restrictor to 31 mm, weight to 1475 lbs. 2024-01-01 P1 Revise Group CN Honda K20A-FD2 Spec Line #35337wordingunclearP1 Group CN Honda K20A-FD2 removes engine modification restrictions; CRB may add intake restrictor if needed. 2024-01-01 SRF Update SRF Rain / Brake Rule #34706otherotherSRF rain/brake light must be Super Bright LEDs Inc. P/N PT-STRB-R24; secondary filament must connect to rain light switch. 2024-01-01 SRF Update SRF Brake Light Rule v1 #34853otherotherSRF brake light must be Super Bright LEDs Inc. P/N PT-STRB-R24, with SCCA Enterprises P/N 180427A pigtail and strobing rain light kit. 2024-01-01 SRF SRF / SRF3 Rule Updates #35268suspension & brakessuspension & brakesSRF adds mandatory front brake ducts 12–36 inches, throttle pedal heel-toe extension, braided stainless flex lines, camber limit 5.0 degrees, radiator opening height 3½ ± ½ inches, rear shift cable clamp P/N WM302007A. 2023-10-01 SRF SRF Radiator Rule Update #34805otheraddedSRF radiator options expanded: Enterprises P/N 480465 with baffle 480464, 480466, or Automotive 1R698 and CU698 allowed if cross-reference equivalent. 2023-07-01 P1 SIR Testing #34354wordingwordingP1 SIR testing: vehicle deemed compliant if it stalls within 3 seconds of the stall test. 2023-07-01 P1 E&O Single Inlet Restrictor abbreviation, etc. #34369wordingwordingP1 intake restrictor rule clarified: flat plate, venturi, or Single Inlet Restrictor required; all intake air must pass through. 2023-07-01 P1 E&O Clean up ducted air provision #34410wordingwordingP1 ducted air rule clarified: top-exit ducted air must pass through heat exchanger, except cockpit opening and engine bay vents. 2023-06-01 SRF Hoosier SRF Wet Front Tire Rule Update #34189tyres & wheelstyres & wheelsSRF wet front tyre changes to Hoosier P/N 46100 P185/60R13 H20 or W2 with 2.5" ground clearance. 2023-05-01 SRF Update SRF Front W2 Rain Tire Part Number #34118tyres & wheelstyres & wheelsSRF front W2 rain tyre Hoosier part number changes from 46100 to 46101 P185/65R13. 2023-04-01 P1 E&O - Correct dimensional equivalents #34018wordingwordingP1 aero height limit, front/rear overhang, and cockpit dimensions corrected to metric-inch equivalents. 2023-03-01 P1 November 2022 Rules Clarification for Suspension Covers #33615aeroslower · aeroP1 suspension covers must have symmetrical upper and lower surfaces, no airfoil cross-sections or angled downforce. 2023-03-01 SRF Update SRF Brake Rule #33469enginefaster · engineSRF removes 1985 Renault Alliance solid front rotor option; restrictor sizes decrease 1mm for newer Kawasaki and multi-brand engines; minimum weights increase to 1100 lbs.
	Super Tour Feb 2023 CALCL232023-02-24									1:06.404Chip Romer · fastest of 3 · top 3 within 1.9s-27.144s (-29.02%)
6 rule changes (SRF: 2, P1: 4)2 engine · 1 aero · 2 wording · 1 other · P1 aerodynamic devices may not extend more than 1cm below lower surfaces rear of front axle; body panels covering suspension must not be airfoil-shaped or create downforce. · P1 forced induction prohibited: turbocharging and supercharging not allowed. · P1 motorcycle-based engines with individual throttle bodies must use flat plate intake restrictors within 4 inches of primary butterfly. · SRF tire rule wording clarified: tires must be run as delivered. · SRF brake rotor minimum thickness reduced from 13.25 mm to 12.20 mm; seals and air filter specs clarified. · P1 bodywork rules clarified: cycle fenders prohibited, side body minimum height at front axle centerline, air ducting for downforce banned.showhide 2022-11-01 P1 Clarify body panel coverage of suspension components #33318aeroaeroP1 aerodynamic devices may not extend more than 1cm below lower surfaces rear of front axle; body panels covering suspension must not be airfoil-shaped or create downforce. 2022-10-01 P1 E&O clarification regarding forced induction #33123engineremoved · engineP1 forced induction prohibited: turbocharging and supercharging not allowed. 2022-08-01 P1 Clarify authorization to use flat plate intake restrictor #32964engineadded · engineP1 motorcycle-based engines with individual throttle bodies must use flat plate intake restrictors within 4 inches of primary butterfly. 2022-06-01 SRF SRF Tire Rule Update #32614wordingwordingSRF tire rule wording clarified: tires must be run as delivered. 2022-06-01 SRF Brake, seal, and air filter clarifications #32670otherfasterSRF brake rotor minimum thickness reduced from 13.25 mm to 12.20 mm; seals and air filter specs clarified. 2022-05-01 P1 E&O Clarification of Bodywork Rules #32468wordingwordingP1 bodywork rules clarified: cycle fenders prohibited, side body minimum height at front axle centerline, air ducting for downforce banned.
	Super Tour Feb 2022 CALCL222022-02-17	2:03.309Lance Spiering · only car	1:58.561Lance Spiering · only car	111.9Lance Spiering						1:33.548Aaron Bailey · fastest of 6 · top 5 within 3.2s-1.427s (-1.50%)	1:34.210Chip Romer · fastest of 6 · top 5 within 4.9s-2.014s (-2.09%)	138.5Aaron Bailey-10.3 mph (-6.9%)	-24.351squal -29.761s	79.5%qual 75.9%
21 rule changes (SRF: 8, P1: 13)4 engine · 3 cars added · 1 induction · 1 tyres & wheels · 10 wording · 2 other · P1 2-cycle 6-cylinder maximum displacement increases to 1725 cc, restrictor shrinks to 40mm, minimum weight drops to 1275 lbs. · SRF wet tyres front P185/65R13 W2 option added; air box clarified as-delivered; SRF3 restrictor plate G301048 mandatory Jan 1 2022; P2 motorcycle engines up to 1005cc with 35mm restrictor, 2009+ stock 1075 lbs, 2008 stock 1025 lbs, modifie… · P1 creates separate spec lines H and I for 2000cc and 2300cc engines at 1400 and 1445 lbs minimum weight respectively. · P1 Staudacher may run 950 lbs minimum weight with 38.5mm flat plate intake restrictor, removing prior weight-linked restrictor rule. · P1 adds 1355cc motorcycle-based engine line C at 1075 lbs minimum weight, no restrictor required. · SRF wet tyres add Hoosier W2 option alongside existing H20 from October 4, 2021. · SRF adds SADEV-SRF3 6-speed sequential transmission option with ratios 3.0–0.92:1 and 3.20 final drive. · SRF seal requirements clarified: seals now must be on driveline components in designated locations; unsealed components removed and inspected by CSR or Enterprises rather than engine shipped for testing. · SRF3 alternator pulley specified as P/N G902130 or G902130A, minimum 12oz. · P1 cockpit opening section allows tonneau covers to meet minimum dimensions; wording clarified on equipment attachment. · P1 Staudacher 1005cc homologated before 1-1-2014 may run 38.5mm flat plate intake restrictor at 950 lbs minimum weight. · P1 Spec Line C: FPIR not required at 1150 lbs, 1355cc max may run without FPIR at 1075 lbs. Spec Line G: up to 2000cc runs 30mm SIR at 1400 lbs, 2300cc runs 30mm SIR at 1445 lbs. · P1 classes B, C, D maximum valves per cylinder set to 4, previously unspecified. · P1 Spec Line A clarifies carburetor induction only, one per cylinder, balance tubes not allowed. · P1 Spec Line H notes clarify peripheral port or bridgeport allowed; wording only. · P1 Elan DP02-spec Mazda MZR sealed engine option removed effective 3/1/2021. · P1 Engine Table Spec Lines C and G change 'inlet restrictor' to 'intake restrictor' terminology. · SRF and SRF3 mandatory identification revised: removed Ford Performance and Blue Oval decals, added Hoosier logo placement. · SRF rear springs limited to P/N 280390 only, previous part numbers no longer allowed; ground clearance wording clarified. · P1 intake manifolds unrestricted unless engine requires flat plate restrictor; no plenums or balance pipes on restricted individual runner manifolds. · SRF Penske shock P/N 280396 bump stop P/N 280407 becomes mandatory, maximum one per shock, effective 05/01/2020.showhide 2022-01-01 P1 Displacement & Weight Change Request for 2-Cycle 6 Cylinder #31609enginefaster · engineP1 2-cycle 6-cylinder maximum displacement increases to 1725 cc, restrictor shrinks to 40mm, minimum weight drops to 1275 lbs. 2021-12-01 SRF Three Updates to SRF Rules #31523otherotherSRF wet tyres front P185/65R13 W2 option added; air box clarified as-delivered; SRF3 restrictor plate G301048 mandatory Jan 1 2022; P2 motorcycle engines up to 1005cc with 35mm restrictor, 2009+ stock 1075 lbs, 2008 stock 1025 lbs, modifie… 2021-09-01 P1 Move 2000cc and 2300cc engine options to individual spec lines #31012cars addedaddedP1 creates separate spec lines H and I for 2000cc and 2300cc engines at 1400 and 1445 lbs minimum weight respectively. 2021-09-01 P1 E&O Spec Line B notes #31095wordingwordingP1 Staudacher may run 950 lbs minimum weight with 38.5mm flat plate intake restrictor, removing prior weight-linked restrictor rule. 2021-08-01 P1 Add 1355cc spec line #30890cars addedaddedP1 adds 1355cc motorcycle-based engine line C at 1075 lbs minimum weight, no restrictor required. 2021-08-01 SRF SRF Wet Tires #30849tyres & wheelsadded · tyres & wheelsSRF wet tyres add Hoosier W2 option alongside existing H20 from October 4, 2021. 2021-08-01 SRF SADEV-SRF3 Transmission #30926cars addedaddedSRF adds SADEV-SRF3 6-speed sequential transmission option with ratios 3.0–0.92:1 and 3.20 final drive. 2021-08-01 SRF SRF Update Maintenance, Repairs and Seals #30961wordingwordingSRF seal requirements clarified: seals now must be on driveline components in designated locations; unsealed components removed and inspected by CSR or Enterprises rather than engine shipped for testing. 2021-06-01 SRF SRF3 Alternator Pulley #30684engineadded · engineSRF3 alternator pulley specified as P/N G902130 or G902130A, minimum 12oz. 2021-05-01 P1 E&O tonneau cover provision in cockpit opening section #30458wordingwordingP1 cockpit opening section allows tonneau covers to meet minimum dimensions; wording clarified on equipment attachment. 2021-05-01 P1 Update Spec Line B Notes #30498wordingwordingP1 Staudacher 1005cc homologated before 1-1-2014 may run 38.5mm flat plate intake restrictor at 950 lbs minimum weight. 2021-05-01 P1 Update Spec Lines C and G notes #30499wordingwordingP1 Spec Line C: FPIR not required at 1150 lbs, 1355cc max may run without FPIR at 1075 lbs. Spec Line G: up to 2000cc runs 30mm SIR at 1400 lbs, 2300cc runs 30mm SIR at 1445 lbs. 2021-05-01 P1 E&O Maximum Valves Per Cylinder #30559engineengineP1 classes B, C, D maximum valves per cylinder set to 4, previously unspecified. 2021-04-01 P1 Clean up Spec Line A notes section #30424wordingwordingP1 Spec Line A clarifies carburetor induction only, one per cylinder, balance tubes not allowed. 2021-04-01 P1 Clean up Spec Line H notes section #30425wordingwordingP1 Spec Line H notes clarify peripheral port or bridgeport allowed; wording only. 2021-03-01 P1 DP02 Sealed 2ltr Engine Option #30038engineremoved · engineP1 Elan DP02-spec Mazda MZR sealed engine option removed effective 3/1/2021. 2021-03-01 P1 E&O restrictor terminology #30285wordingwordingP1 Engine Table Spec Lines C and G change 'inlet restrictor' to 'intake restrictor' terminology. 2021-03-01 SRF Mandatory identification: #30223wordingwordingSRF and SRF3 mandatory identification revised: removed Ford Performance and Blue Oval decals, added Hoosier logo placement. 2020-12-01 SRF SRF Shocks, Springs and Ride Height. #29688otherotherSRF rear springs limited to P/N 280390 only, previous part numbers no longer allowed; ground clearance wording clarified. 2020-05-01 P1 E&O minimum weights and intake manifolds #28731inductioninductionP1 intake manifolds unrestricted unless engine requires flat plate restrictor; no plenums or balance pipes on restricted individual runner manifolds. 2020-05-01 SRF SRF Bump Stop Correction #27019wordingwordingSRF Penske shock P/N 280396 bump stop P/N 280407 becomes mandatory, maximum one per shock, effective 05/01/2020.
	Super Tour Feb 2020 ST20FEB212020-02-21									1:34.975Jim Devenport · fastest of 4 · top 4 within 7.1s-2.683s (-2.75%)	1:36.224Jim Devenport · fastest of 4 · top 4 within 5.9s-2.632s (-2.66%)	148.8Johnnie Crean+15.3 mph (+11.5%)
16 rule changes (SRF: 5, P1: 11)1 aero · 1 cars added · 1 engine · 1 removed · 1 tyres & wheels · 1 weight · 9 wording · 1 other · P1 sealed 2.0L Elan DP02-spec Mazda option removal date extended from 1/1/2020 to 1/1/2021. · P1 sealed 2.0 MZR engine removed effective 1/1/2020; competitors may run it under Spec Line G. · P1 Spec Line F: Restricted 2.0L Group becomes CN-spec Honda K20A-FD2, 2000cc, 1400 lbs minimum. · SRF rain and brake rule supersedes GCR 9.3.32.B.2 effective 1/1/2024 through 12/31/2024. · SRF adds tire warmer prohibition and specifies Hoosier dry and wet tire part numbers. · SRF front nose weight minimum reduced from 35 to 32 lbs. · SRF2 becomes Regional Only; SRF3 nomenclature changed from GEN3 to Ford 1.6L conversion; SRF and SRF3 no longer compete together for points. · P1 traction control prohibited. · P1 permits mechanical, solenoid, and air-shifters; prohibits electronic pre-selection and multi-wheel power. · P1 minimum bodywork height rule moved and restated with new 115cm aerodynamic part height limit. · P1 consolidates fender louver rules into one section; removes duplicate allowance for louvers and clarifies brake and engine air ducts are permitted. · SRF drivers may now use Dash Windscreen Kit P/N 1180103 or P/N 180102. · P1 anti-intrusion panels now allowed anywhere on chassis sides instead of specified locations. · P1 bodywork wording clarified: comfort and safety for driver and passenger or driver only. · P1 Engine Table reference cleaned up; no performance change. · P1 Mazda Renesis Rotary engine spec line removed from Engine Table.showhide 2020-02-01 P1 Extend date for removing sealed DP02-spec 2.0L option #28046wordingunclearP1 sealed 2.0L Elan DP02-spec Mazda option removal date extended from 1/1/2020 to 1/1/2021. 2020-01-01 P1 Remove sealed DP02-spec 2.0 MZR spec #26753removedremovedP1 sealed 2.0 MZR engine removed effective 1/1/2020; competitors may run it under Spec Line G. 2020-01-01 P1 Update Revised Spec Line F #27745engineengineP1 Spec Line F: Restricted 2.0L Group becomes CN-spec Honda K20A-FD2, 2000cc, 1400 lbs minimum. 202-01-01 SRF SRF Rain / Brake Rule - BoD approved as follows #34958wordingwordingSRF rain and brake rule supersedes GCR 9.3.32.B.2 effective 1/1/2024 through 12/31/2024. 2019-12-01 SRF SRF Tire Warmer Rule #27622tyres & wheelstyres & wheelsSRF adds tire warmer prohibition and specifies Hoosier dry and wet tire part numbers. 2019-12-01 SRF SRF / SRF3 Nose Weight Reduction #27706weightfaster · weightSRF front nose weight minimum reduced from 35 to 32 lbs. 2019-12-01 SRF SRF / SRF3 Majors & Regional Class Updates #27723wordingwordingSRF2 becomes Regional Only; SRF3 nomenclature changed from GEN3 to Ford 1.6L conversion; SRF and SRF3 no longer compete together for points. 2019-08-01 P1 E&O Transmissions #27098wordingwordingP1 traction control prohibited. 2019-07-01 P1 E&O Transmissions #27005otheraddedP1 permits mechanical, solenoid, and air-shifters; prohibits electronic pre-selection and multi-wheel power. 2019-07-01 P1 Move minimum height provision to #27031wordingwordingP1 minimum bodywork height rule moved and restated with new 115cm aerodynamic part height limit. 2019-07-01 P1 Remove duplicative fender louver provision #27033wordingwordingP1 consolidates fender louver rules into one section; removes duplicate allowance for louvers and clarifies brake and engine air ducts are permitted. 2019-07-01 SRF SRF Dash Windscreen Kit #27028aeroadded · aeroSRF drivers may now use Dash Windscreen Kit P/N 1180103 or P/N 180102. 2019-05-31 P1 Missing word E&O #26919wordingwordingP1 anti-intrusion panels now allowed anywhere on chassis sides instead of specified locations. 2019-05-31 P1 E&O correction to GCR 9.1.8.C.C. #26927wordingwordingP1 bodywork wording clarified: comfort and safety for driver and passenger or driver only. 2019-05-01 P1 Clean up reference to engine table #26648wordingwordingP1 Engine Table reference cleaned up; no performance change. 2019-05-01 P1 Remove redundant spec line #26692cars addedremoved · cars addedP1 Mazda Renesis Rotary engine spec line removed from Engine Table.
	Super Tour Apr 2019 ST19APR262019-04-26									1:37.658Jim Devenport · fastest of 3 · top 3 within 8.6s-1.339s (-1.35%)	1:38.856Jim Devenport · fastest of 3 · top 3 within 4.2s+1.745s (+1.80%)	133.5Jeffrey Lederman
6 rule changes (P1: 6)6 wording · P1 Staudacher and Honda K20A-FD2 engine table wording clarified; no performance change. · P1 closed cockpit single-seat cars remain prohibited; rule moved from subsection J.5 to B.4. · P1 engine table reference corrected from 'above' to 'below'; ETC/FBW/DBW throttle wording clarified on sensor and fail-safe requirements. · P1 removes TIR inlet restrictor option; deletes requirement for single turbo/supercharger unit with single restrictor. · P1 CN-spec Honda K20A-FD2 clarified: stock OEM parts required, no machining allowed. · P1 engine rules correct grammar and remove head designs from specification table.showhide 2019-04-01 P1 Clean Up Engine Table Language #26590wordingwordingP1 Staudacher and Honda K20A-FD2 engine table wording clarified; no performance change. 2019-03-01 P1 Move single-seat closed cockpit provision to #26376wordingwordingP1 closed cockpit single-seat cars remain prohibited; rule moved from subsection J.5 to B.4. 2019-02-01 P1 Correct errors in GCR section 9.1.8.C.J #26144wordingwordingP1 engine table reference corrected from 'above' to 'below'; ETC/FBW/DBW throttle wording clarified on sensor and fail-safe requirements. 2019-01-01 P1 Remove redundant inlet restrictor provisions #25877wordingwordingP1 removes TIR inlet restrictor option; deletes requirement for single turbo/supercharger unit with single restrictor. 2019-01-01 P1 Clarify Honda K20A-FD2 parts requirement #25949wordingwordingP1 CN-spec Honda K20A-FD2 clarified: stock OEM parts required, no machining allowed. 2019-01-01 P1 Correct GCR section 9.1.8.C.J errors #25966wordingwordingP1 engine rules correct grammar and remove head designs from specification table.
	Super Tour Apr 2018 BUTTRA182018-04-27									1:38.997Chip Romer · fastest of 6 · top 5 within 7.8s+2.677s (+2.78%)	1:37.111Chip Romer · fastest of 6 · top 5 within 13.4s-0.316s (-0.32%)
No rule changes on record between these events
	Super Tour Apr 2017 BUTTRA172017-04-28				1:44.060Vince Balch · fastest of 8 · top 5 within 18.6s	2:01.122Mike Miserendino · fastest of 7 · top 5 within 1.8s				1:36.320Jim Devenport · fastest of 5 · top 5 within 6.9s	1:37.427Parker Nicklin · fastest of 5 · top 5 within 6.2s

About this data

Best is the class's fastest lap in that event's qualifying or race sessions, with the driver who set it, how many cars set a time that session and how close the top five were; a best from fewer than three cars is greyed. With two or more classes, "vs" is the gap of each class's best to the first class's at the same event. "% of F500" is the class's best as a share of F500's best at the same event (100% is level, less is quicker): weather and track condition move every class together, so this compares across years where the raw times do not. It still breaks when F500's own field changes or one session was wet and another dry. Newest event first. The coloured figure under each value is the change from the previous event that has one (green is quicker, red slower). Whole laps only, so events with different sector layouts still compare. Weather and track condition are not accounted for.